Researchers have documented a method for working out ATM PIN numbers using residual traces of heat left on keypads after they have been touched by a person’s fingers. Thermal imaging camera could be used to visually record the heat on each key as a way of snooping PINs. Even without being able to detect the precise order of the PINs entered, just knowing which four numbers were involved would reduce the number of PINs from 10,000 combinations to only 24. If used in large-scale attacks the technique would outperform the tradition criminal method of shoulder-surfing PINs or recording them from a distance.”]